Preparation method of a composite three-roller two-pressure combined paper conveying belt for producing thermal sublimation paper

Abstract

The application provides a preparation method of a composite three-roller two-press combined paper conveying belt for producing thermal sublimation paper, wherein bleached kraft wood pulp and coniferous wood pulp are mixed and beaten, cationic starch, dry strength agent, wet strength agent, alkenyl succinic anhydride, positive high molecular polyacrylamide and colloidal silicon dioxide are added into the pulp, long net and top net are formed, and then composite three-roller two-press mode is used for pressing, the three rollers are suction transfer pressing vacuum rollers, center rollers and boot pressing rollers, the two presses are the first press dewatering and the second press dewatering, the wet paper web is completely contacted with the belt and dried together with the belt which is synchronous with the center roller, closed paper guiding is performed, surface sizing is performed, drying is performed, soft calendering is performed, and winding is performed, so that the finished product is obtained. The coating of the thermal sublimation paper produced by the application can be reduced to 3gsm, the smoothness can reach more than 200s, the transfer rate is improved, the color on the cloth is good, and the paper prepared by the method of the application can further reduce the coating amount and reduce the production cost.

Description

Technical Field

[0001] This invention relates to the field of transfer paper technology, specifically to a method for preparing thermal sublimation paper using a composite three-roller two-pressure combined paper conveyor belt. Background Technology

[0002] The pursuit of personalized, efficient, environmentally friendly, and high-precision printing technologies meets current production demands, leading to the rapid development of digital printing technology based on sublimation transfer paper. The rapid growth of the digital printing market and the upgrading of printer technology place higher demands on sublimation transfer paper. Sublimation transfer paper production has now shifted from off-machine coating to in-machine papermaking. In-machine papermaking offers higher efficiency, significantly reducing production costs and saving resources and energy.

[0003] Currently, companies primarily producing sublimation transfer paper in-machine are Xianhe, Jianghe, Wuzhou, and Guanhao, with Xianhe Paper holding the largest market share. However, in mainstream production methods, the maximum machine speed can only reach 600-700 m / min, limiting production efficiency. Therefore, the mainstream pressing methods for in-machine sublimation paper production are relatively simple, mainly using 606 standard pressing or positive / light pressing. Forcibly increasing the machine speed can lead to material sticking and quality issues such as white spots on the printed paper. Currently, the domestic patents related to the production of sublimation paper include: Patent "An Ultra-thin Sublimation Transfer Paper and Its Preparation Method", which requires two coatings, one isolation layer and one functional coating, resulting in high production costs and problems such as poor paper flatness and low efficiency; Patent "Base Paper for Sublimation Transfer Paper and Sublimation Transfer Paper", which can only produce sublimation transfer base paper in the machine and cannot produce sublimation transfer paper in one go; Patent "A Double-sided Sublimation Transfer Paper" requires multiple coatings to meet the technical requirements of sublimation transfer paper. Existing sublimation transfer paper production technology limits the increase in printing speed. Specifically, under current pressing methods and paper drawing conditions, the overall moisture content of the paper web exiting the press cannot exceed 40%, and the smoothness of the base paper is relatively low. This necessitates increasing the coating amount or adding an extra coating layer at the sizing end to improve the coating's opacity. Since sublimation primarily uses CMC (carboxymethyl cellulose) coatings, which are difficult to dry, increasing the coating amount due to poor paper surface smoothness further limits the drying rate of the paper web in the sizing section, preventing the increase in printing speed, resulting in low production efficiency and high unit production costs. To overcome the speed bottleneck and improve production efficiency, it is necessary to improve issues such as paper web dehydration in the press section and paper drawing. Therefore, it is necessary to provide a technology that combines a composite pressing method with closed-loop paper drawing technology for application in the production of sublimation transfer paper. Summary of the Invention

[0004] Therefore, this invention proposes a method for preparing a composite three-roller two-pressure combined paper conveyor belt for producing thermal sublimation paper, which solves the above-mentioned problems.

[0005] The technical solution of the present invention:

[0006] A method for preparing a composite three-roller two-pressure combined paper feed belt for the production of sublimation paper, characterized by comprising the following preparation steps:

[0007] S1. Mix bleached sulfate hardwood pulp and bleached sulfate softwood pulp to obtain oven-dry pulp. Beat the oven-dry pulp to obtain raw pulp.

[0008] S2. Add cationic starch, dry strength agent, wet strength agent, alkenyl succinic anhydride, cationic polymeric polyacrylamide and colloidal silica to the pulp to obtain papermaking raw liquor;

[0009] S3. The papermaking liquor is formed by forming a long wire and a top wire to obtain a pre-formed wet paper web;

[0010] S4. The pre-formed wet paper web is pressed using a composite three-roll two-press method. The three rolls are a suction-shift press vacuum roll, a center roll, and a shoe press roll. The two presses are a first press for dewatering and a second press for dewatering, resulting in a wet paper web. The entire wet paper web is then fully contacted with a belt and fed into the pre-drying section in sync with the center roll. After drying, the paper web is obtained through a completely closed-loop feeding system. The suction-shift press vacuum roll is polyurethane-coated with through holes and grooves, and is designed with three vacuum chambers. The suction-shift press vacuum roll has a steel roll shell, and the shoe press roll uses a steel roller and a steel shoe with a shoe cover.

[0011] S5. Apply sizing to the surface of the paper web, dry it again, calender it gently, and curl it to obtain the finished paper.

[0012] Further, in step S1, the bleached sulfate hardwood pulp accounts for 70%-100% by mass, and the bleached sulfate softwood pulp accounts for 0%-30% by mass.

[0013] Further, in step S2, the dry strength agent is polyacrylamide and its derivatives; the wet strength agent is polyamide polyepoxychloropropane resin.

[0014] Further, in step S2, the mass ratio of cationic starch to oven-dried slurry is 5-15:1000; the mass ratio of dry strength agent (polyacrylamide and its derivatives) to oven-dried slurry is 6-20:1000; the mass ratio of wet strength agent to oven-dried slurry is 10-30:1000; the mass ratio of alkenyl succinic anhydride to oven-dried slurry is 1.0-1.5:1000; the mass ratio of cationic polymeric polyacrylamide to oven-dried slurry is 0.05-0.1:1000; and the mass ratio of colloidal silica to oven-dried slurry is 2.0-4.0:1000.

[0015] Further, in step S3, the mass concentration of the papermaking liquor is 0.3%-0.7%, the pulp-to-wire ratio is 1-1.1:1, and the dryness of the pre-formed paper web is 17%-19%.

[0016] Further, in step S4, the first pressing has a linear pressure of 85-90 KN / M, and the second pressing has a linear pressure of 1000-1250 KN / M.

[0017] Further, in step S4, during the drying process, the moisture content of the paper exiting the pressing section is greater than 42%, and the moisture content of the paper web ranges from 4.0% to 7.0%.

[0018] Further, in step S5, the surface sizing is performed by applying enzymatically cleaved starch to the surface facing upwards of the paper web. The solid content of the surface sizing solution is 8%-15%, the viscosity is 7cps-17cps, and the sizing amount is 0.5gsm-1.5gsm. The surface sizing is performed on the surface facing downwards of the paper web by applying a thermal sublimation coating. The solid content of the surface sizing solution is 20%-40%, the viscosity is 500cps-3000cps, and the sizing amount is 2.8gsm-3.2gsm.

[0019] Further, in step S5, the re-drying includes infrared drying and oven drying, and the moisture content of the finished paper is 3%-8%.

[0020] Furthermore, in step S5, the smoothness of the finished paper is 50s-500s, and the transfer rate is >75%.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] (1) The present invention uses a long wire paper machine for papermaking and a composite three-roll two-press method for pressing. It adopts a composite pressing method of vacuum pressing and shoe pressing. After two pressings for dehydration and drying, the paper is drawn in a completely closed manner, which greatly improves the paper web drawing success rate and thus improves production efficiency.

[0023] (2) The present invention adopts a pressing method, which can greatly improve the dryness of the paper web exiting the pressing section and increase the speed of the paper machine. Because the paper web enters the drying section in a smooth and flat belt, the functional surface of the paper will have a high degree of smoothness, which can further reduce the amount of coating and reduce production costs.

[0024] (3) The sublimation paper produced by this invention can achieve a smoothness of more than 200s, which is not currently available in the mainstream market. This improves the transfer rate, provides good color presentation, and reduces the amount of sublimation coating to 3gsm. Attached Figure Description

[0025] Figure 1This is a diagram of a composite three-roll, two-pressure structure. ① is the shoe pressure roll; ② is the paper conveyor belt; ③ is the center roll; ④ is the suction-transfer vacuum press roll.

[0026] Figure 2 The following are comparison charts of transfer rates: (I) is the transfer rate chart for Example 1; (II) is the transfer rate chart for Control 1; (III) is the transfer rate chart for Control 2. The first row of each chart (①) shows the effect of transfer onto standard polyester fabric, the second row of each chart (②) shows the effect of printing onto paper, and the second row of each chart (③) shows the amount of ink remaining on the paper after transfer.

[0027] Figure 3 SEM (Scanning Electron Microscope) scan image of Example 1

[0028] Figure 4 SEM (Scanning Electron Microscope) scan of control 1

[0029] Figure 5 SEM (Scanning Electron Microscope) scan of control 2 Detailed Implementation

[0030] To better understand the technical content of this invention and to provide a clear and complete description of the technical solution, specific embodiments are provided below to further illustrate the invention. The following are only some embodiments of this invention.

[0031] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available. Unless otherwise specified, all experimental methods used in the embodiments of this invention are conventional methods. To better understand the technical content of this invention, specific embodiments, comparative examples, and specific experiments are provided below to further illustrate this invention.

[0032] Example 1

[0033] A composite three-roller two-pressure combined paper conveyor belt technology for producing 29gsm sublimation paper

[0034] (i) Mix 80% bleached sulfate hardwood pulp and 20% bleached sulfate softwood pulp to obtain oven-dry pulp. Beat the oven-dry pulp to obtain raw pulp.

[0035] (II) Cationic starch, dry strength agent (polyacrylamide and its derivatives), polyamide-polyepoxychloropropane resin, alkenyl succinic anhydride, cationic polymeric polyacrylamide, and colloidal silica are added to the original pulp to obtain papermaking raw solution; wherein, the mass ratio of cationic starch to oven-dry pulp is 8:1000; the mass ratio of dry strength agent (polyacrylamide and its derivatives) to oven-dry pulp is 10:1000; the mass ratio of polyamide-polyepoxychloropropane resin to oven-dry pulp is 15:1000; the mass ratio of alkenyl succinic anhydride to oven-dry pulp is 1.3:1000; the mass ratio of cationic polymeric polyacrylamide to oven-dry pulp is 0.05:1000; and the mass ratio of colloidal silica to oven-dry pulp is 2:1000.

[0036] (III) The papermaking liquor with a mass concentration of 0.45% is formed by the long wire and the top wire, and dewatered to form a fiber layer. The water in the pulp is drawn out through the long wire and the top wire to form a wet paper web with uniform moisture. The pulp-wire speed ratio is 1.05:1, and the dryness of the pre-formed wet paper web is 18%.

[0037] (iv) The pre-formed wet paper web is subjected to a compound three-roll two-press method. The three rolls are a vacuum roll, a center roll, and a shoe roll. The two presses are divided into a first press for dewatering and a second press for dewatering. The pre-formed wet paper web is drawn into the press section as a whole by the vacuum roll for the first press (i.e., the press zone where the vacuum roll and the center roll are combined). After the first press (linear pressure 90KN / M), it is dewatered and then enters the second press zone (center roll and shoe roll) for the second press (linear pressure 11). After two dewatering processes (00KN / M), the pre-formed wet paper web is fully exposed to the belt and fed into the pre-drying section by a belt synchronized with the center roll. The entire paper web enters the pre-drying section, and the paper web exits the pressure section with a moisture content of 42%, resulting in a wet paper web. The paper web has a moisture content range of 5.0%. The suction press vacuum roll is polyurethane coated with through holes and grooves, and is designed with three vacuum chambers. The vacuum roll uses a steel roll shell, and the shoe press roll uses a steel roller and steel shoe, with a shoe cover.

[0038] (V) Apply sizing to the paper web surface. Apply sizing to the TWS side (paper web facing up, i.e., the side of the paper web with the sizing roller) and coat with enzymatically cleaved starch. The solid content of the surface sizing solution is 10%, the viscosity is 12 cps, and the sizing amount is 0.8 gsm. Apply sizing to the BWS side (paper web facing down, i.e., the side of the paper web with the sizing roller) and coat with a thermal sublimation coating. The solid content of the surface sizing solution is 24%, the viscosity is 1372 cps, and the sizing amount is 3 gsm. Perform infrared drying and oven drying again, soft calendering + curling, linear pressure is 40 kN / m, temperature is 60℃, and after finishing and flattening the paper web, wind it up at a speed of 841 m / min to obtain the finished paper. The finished paper has a basis weight of 29 gsm, a thickness of 33 μm, a density of 0.89 g / cm3, a smoothness of 272 s, and a transfer rate greater than 75%.

[0039] Example 2

[0040] A composite three-roller two-pressure combined paper conveyor belt technology for producing 31gsm thermal sublimation paper

[0041] (i) Mix 85% bleached sulfate hardwood pulp and 15% bleached sulfate softwood pulp to obtain an oven-dry pulp. Beat the oven-dry pulp to obtain raw pulp.

[0042] (II) Cationic starch, dry strength agent (polyacrylamide and its derivatives), polyamide-polyepoxychloropropane resin, alkenyl succinic anhydride, cationic polymeric polyacrylamide, and colloidal silica are added to the original pulp to obtain papermaking raw solution; wherein, the mass ratio of cationic starch to oven-dry pulp is 9:1000; the mass ratio of dry strength agent (polyacrylamide and its derivatives) to oven-dry pulp is 12:1000; the mass ratio of polyamide-polyepoxychloropropane resin to oven-dry pulp is 15:1000; the mass ratio of alkenyl succinic anhydride to oven-dry pulp is 1:1000; the mass ratio of cationic polymeric polyacrylamide to oven-dry pulp is 0.05:1000; and the mass ratio of colloidal silica to oven-dry pulp is 2.5:1000.

[0043] (III) The papermaking liquor with a mass concentration of 0.5% is formed by the long wire and the top wire, and dewatered to form a fiber layer. The water in the pulp is drawn out through the long wire and the top wire to form a wet paper web with uniform moisture. The pulp-wire speed ratio is 1.04:1, and the dryness of the pre-formed wet paper web is 18%.

[0044] (iv) The pre-formed wet paper web is subjected to a compound three-roll two-press method. The three rolls are a vacuum roll, a center roll, and a shoe roll. The two presses are divided into a first press for dewatering and a second press for dewatering. The pre-formed wet paper web is drawn into the press section as a whole by the vacuum roll for the first press (i.e., the press zone where the vacuum roll and the center roll are combined). After the first press (linear pressure 85KN / M), it is dewatered and then enters the second press zone (center roll and shoe roll) for the second press (linear pressure 10KN / M). After two dewatering processes (00KN / M), the pre-formed wet paper web is fully exposed to the belt and fed into the pre-drying section by a belt synchronized with the center roll. The entire paper web enters the pre-drying section, and the paper web exits the pressure section with a moisture content of 42%, resulting in a wet paper web. The paper web has a moisture content range of 5.0%. The suction press vacuum roll is polyurethane coated with through holes and grooves, and is designed with three vacuum chambers. The vacuum roll uses a steel roll shell, and the shoe press roll uses a steel roller and steel shoe, with a shoe cover.

[0045] (V) Apply sizing to the paper web surface. Apply sizing to the TWS side (paper web facing upwards, i.e., the side of the paper web attached to the sizing roller), using enzymatically cleaved starch. The solid content of the surface sizing solution is 12%, the viscosity is 15 cps, and the sizing amount is 1 gsm. Apply sizing to the BWS side (paper web facing downwards, i.e., the side of the paper web attached to the sizing roller), using a thermal sublimation coating. The solid content of the surface sizing solution is 28%, the viscosity is 2120 cps, and the sizing amount is 3.5 gsm. Perform infrared drying and oven drying again, followed by soft calendering and curling at a linear pressure of 20 kN / m and a temperature of 50°C. After finishing and flattening the paper web, wind it up at a speed of 800 m / min to obtain the finished paper. The finished paper has a basis weight of 31 gsm, a thickness of 37.5 μm, and a density of 0.82 g / cm. 3 Smoothness 73s, transfer rate greater than 75%.

[0046] Example 3

[0047] A composite three-roller two-pressure combined paper conveyor belt technology for producing 35gsm thermal sublimation paper

[0048] (a) Mix 90% bleached sulfate hardwood pulp and 10% bleached sulfate softwood pulp to obtain oven-dry pulp. Beat the oven-dry pulp to obtain raw pulp.

[0049] (II) Cationic starch, dry strength agent (polyacrylamide and its derivatives), polyamide-polyepoxychloropropane resin, alkenyl succinic anhydride, cationic polymeric polyacrylamide, and colloidal silica are added to the original pulp to obtain papermaking raw solution; wherein, the mass ratio of cationic starch to oven-dry pulp is 10:1000; the mass ratio of dry strength agent (polyacrylamide and its derivatives) to oven-dry pulp is 15:1000; the mass ratio of polyamide-polyepoxychloropropane resin to oven-dry pulp is 10:1000; the mass ratio of alkenyl succinic anhydride to oven-dry pulp is 1.5:1000; the mass ratio of cationic polymeric polyacrylamide to oven-dry pulp is 0.05:1000; and the mass ratio of colloidal silica to oven-dry pulp is 3:1000.

[0050] (III) The papermaking liquor with a mass concentration of 0.55% is formed by the long wire and the top wire, and dewatered to form a fiber layer. The moisture of the pulp is drawn out through the long wire and the top wire to form a wet paper web with uniform moisture. The pulp-wire speed ratio is 1.03:1, and the dryness of the pre-formed wet paper web is 18%.

[0051] (iv) The pre-formed wet paper web is subjected to a compound three-roll two-press method. The three rolls are a vacuum roll, a center roll, and a shoe roll. The two presses are a first press for dewatering and a second press for dewatering. The pre-formed wet paper web is drawn into the press section as a whole by the vacuum roll for the first press (i.e., the press zone where the vacuum roll and the center roll are combined). After the first press (linear pressure 90KN / M), it is dewatered and then enters the second press zone (center roll and shoe roll) for the second press (linear pressure 12). After two dewatering processes (00KN / M), the pre-formed wet paper web is fully exposed to the belt and fed into the pre-drying section by a belt synchronized with the center roll. The entire paper web enters the pre-drying section, and the paper web exits the pressure section with a moisture content of 42%, resulting in a wet paper web. The paper web has a moisture content range of 5.0%. The suction press vacuum roll is polyurethane coated with through holes and grooves, and is designed with three vacuum chambers. The vacuum roll uses a steel roll shell, and the shoe press roll uses a steel roller and steel shoe, with a shoe cover.

[0052] (V) Apply sizing to the paper web surface. Apply sizing to the TWS side (paper web facing up, i.e., the side of the paper web to which the sizing roller is attached) and coat with enzymatically cleaved starch. The solid content of the surface sizing solution is 12%, the viscosity is 15 cps, and the sizing amount is 1 gsm. Apply sizing to the BWS side (paper web facing down, i.e., the side of the paper web to which the sizing roller is attached) and coat with a thermal sublimation coating. The solid content of the surface sizing solution is 28%, the viscosity is 2120 cps, and the sizing amount is 3.5 gsm. Perform infrared drying and oven drying again, soft calendering + curling, linear pressure is 30 kN / m, temperature is 60℃, and after finishing and flattening the paper web, wind it up at a speed of 780 m / min to obtain the finished paper. The finished paper has a basis weight of 34.7 gsm, a thickness of 43.6 μm, and a density of 0.80 g / cm. 3Smoothness 75s, transfer rate greater than 75%.

[0053] Comparison 1: Commercially available sublimation paper (29gsm sublimation paper), manufactured by Wuzhou Paper Industry.

[0054] Comparison 2: Commercially available sublimation paper (31gsm sublimation paper), manufactured by Xianhe Paper Industry.

[0055] Comparison 3: Commercially available sublimation paper (35gsm sublimation paper), manufactured by Jianghe Paper Industry.

[0056] Comparative tests were conducted on the paper properties of the examples and the control, as shown in Table 1. The printability and testing methods for the printing paper were in accordance with GB / T 34688-2017, and the same method was used for both examples and the control. The coating weight was determined using the water washing method. The results showed that the coating weight of Examples 1-3 was 1-1.6 gsm lower than the control, which could significantly reduce coating costs. Smoothness was measured using a Bekk smoothing instrument. The smoothness of the paper in Examples 1-3 was more than double that of the control, and the transverse elongation was significantly better. The transverse elongation was measured by soaking paper strips in water for 15 minutes and then calculating the elongation rate. Lower elongation is better, indicating less transverse deformation of the paper. The uniformity of the paper in Examples 1-3 was significantly better than the control group. Uniformity was analyzed using a UMT optical uniformity instrument to examine the internal fiber clumps of the paper. A higher value indicates more clumps and poorer uniformity.

[0057] Table 1

[0058]

[0059]

[0060] Transfer rate comparison chart ( Figure 2 The results show that, comparing the first row of patterns in each image (① the effect of transfer to standard polyester fabric), there is basically no difference between the embodiment and controls 1 and 2. Comparing the second row of patterns in each image (② the effect of printing on paper), the printed pattern of the embodiment is delicate and without ink smudging, while the control shows ink smudging. Comparing the second row of patterns in each image (③ the amount of residual ink on the paper after transfer), the amount of residual ink on the paper of the embodiment is significantly lower than that of controls 1 and 2, indicating that the ink transfer effect of the embodiment is better. A comparison of the paper surface morphology of the embodiment and competing products under SEM shows that, from the SEM images of the embodiment and the control, the coating amount on the surface of the paper of the embodiment is significantly lower than that of the control, with a measured coating amount of about 3 gsm, while the control is basically 4-5 gsm. Therefore, the sublimation paper prepared by the method of this invention produces a delicate printed pattern without ink smudging, with a significantly reduced amount of residual ink, and a better ink transfer effect, resulting in superior printing performance.

[0061] The above description is merely an example of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a composite three-roller, two-pressure combined paper conveyor belt for the production of sublimation paper, characterized in that, The preparation steps include the following: S1. Mix bleached sulfate hardwood pulp and bleached sulfate softwood pulp to obtain oven-dry pulp. Beat the oven-dry pulp to obtain raw pulp. S2. Add cationic starch, dry strength agent, wet strength agent, alkenyl succinic anhydride, cationic polymeric polyacrylamide and colloidal silica to the pulp to obtain papermaking raw liquor; The dry strength agent is polyacrylamide and its derivatives; the wet strength agent is polyamide-polyepoxychloropropane resin. S3. The papermaking liquor is formed by forming a long wire and a top wire to obtain a pre-formed wet paper web; S4. The pre-formed wet paper web is pressed using a composite three-roll two-press method. The three rolls are a suction-shift press vacuum roll, a center roll, and a shoe press roll. The two presses are a first press for dewatering and a second press for dewatering, resulting in a wet paper web. The entire wet paper web is then fully contacted with a conveyor belt and fed into the pre-drying section in sync with the center roll. The paper is then dried using a completely closed-loop paper feeding system. The suction-shift press vacuum roll is polyurethane-coated and designed with three vacuum chambers. The suction-shift press vacuum roll has a steel roll shell, and the shoe press roll uses a steel roller and a steel shoe with a shoe cover. The first pressing and dehydration stage has a linear pressure of 85-90 KN / M, and the second pressing and dehydration stage has a linear pressure of 1000-1250 KN / M. During the drying process, the moisture content of the paper exiting the pressing section is greater than 42%, and the moisture content of the paper web ranges from 4.0% to 7.0%. S5. Apply sizing to the surface of the paper web, dry it again, calender it softly, and curl it to obtain the finished paper. The smoothness of the finished paper is 50s-500s, and the transfer rate is >75%. The surface sizing is performed on the surface of the paper web facing upwards, applying enzymatically cleaved starch. The solid content of the surface sizing solution is 8%-15%, the viscosity is 7cps-17cps, and the sizing amount is 0.5gsm-1.5gsm. The surface sizing is performed on the surface of the paper web facing downwards, applying a thermal sublimation coating. The solid content of the surface sizing solution is 20%-40%, the viscosity is 500cps-3000cps, and the sizing amount is 2.8gsm-3.2gsm.

2. The method for preparing a composite three-roller two-pressure combined paper conveyor belt for producing sublimation paper as described in claim 1, characterized in that, In step S1, the bleached sulfate hardwood pulp accounts for 70%-100% of the total mass, and the bleached sulfate softwood pulp accounts for 0%-30% of the total mass.

3. The method for preparing a composite three-roller two-pressure combined paper conveyor belt for producing sublimation paper as described in claim 1, characterized in that, In step S2, the mass ratio of cationic starch to oven-dried slurry is 5-15:1000; the mass ratio of dry strength agent to oven-dried slurry is 6-20:1000; the mass ratio of wet strength agent to oven-dried slurry is 10-30:1000; the mass ratio of alkenyl succinic anhydride to oven-dried slurry is 1.0-1.5:1000; the mass ratio of cationic polymeric polyacrylamide to oven-dried slurry is 0.05-0.1:1000; and the mass ratio of colloidal silica to oven-dried slurry is 2.0-4.0:1000.

4. The preparation method of a composite three-roll two-pressure combined paper conveyor belt for producing thermal sublimation paper as described in claim 1, in step S3, the mass concentration of the papermaking liquor is 0.3%-0.7%, the pulp-to-wire ratio is 1-1.1:1; and the dryness of the pre-formed wet paper web is 17%-19%.

5. The preparation method of a composite three-roller two-pressure combined paper conveyor belt for producing sublimation paper as described in claim 1, step S5, the re-drying includes infrared drying and oven drying, and the moisture content of the finished paper is 3%-8%.

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